Detent



Oct. 23, 1962 H. s. EADlE 3,059,497

' DETENT Filed March 9, 1960 IN V EN TOR.

United States Patent This invention relates to an improved detent andmore particularly to an improved detent mechanism, the preferredembodiment of which is especially adapted for multiposition rotaryelectrical switches of the type generally found in electrical andelectronic equipment such as radios and television receivers.

In electronic equipment it is extremely important that switches closepositively and quickly to avoid arcing and burning of contacts,unnecessary noise in signal circuits and faulty transmission.

It has been common in the switch art to employ toggle switches andvarious overcenter devices to insure positive closure of contacts andquick action. The fundamental desideratum of all switch mechanisms isquick, positive closure in the nature of a snap action. While toggleswitches attain this and are usually satisfactory for twopositioncontrol, rotary switches are usually employed where a plurality ofswitch positions or signal channels are desired. In typical rotaryswitches employed in electronic equipment there are twelve possiblecontrol positions which are defined by a detent mechanism. Dependingupon the construction and orientation of the switch contacts, one ormore of these switch positions may be inactive and unused.

Various means have been employed for locating a to tary switch portionin a plurality of predetermined positions relative to spaced fixedcontacts. These have included variousindentations cooperating withballs, rollers, lever arms and the like. However, none of the detentmechanisms heretofore known has proven wholly satisfactory in that theyhave not insured a snap action in the nature of a toggle or overcenteraction and thus they have not uniformly provided quick and positivecontact closure. They have usually been susceptible to quiescent orstable positioning at dead center between two contact positions. Themore satisfactory detent mechanisms heretofore known have been quitecostly and diflicult to manufacture.

It is therefore one object of this invention to provide an improveddetent which is extremely simple in construction but provides positivepositioning of two relatively rotatable parts.

It is a further object of this invention to provide an v improved detentmechanism for use with rotary electrical switches wherein the switch maybe actuated positively and quickly to a predetermined plurality ofcontact positions.

Another object of this invention is the provision of a detent mechanismfor a rotary electrical switch in which the rotary portion thereof willnaturally seat in one of a plurality of predetermined positions and willbe free of stable dead center orientation between the predeterminedpositions.

It is still another object of this invention to provide a detent for anelectrical switch which is simple and inexpensive to construct and whichis virtually free of maintenance problems.

Another object of this invention is the provision of an improved detentfor rotary electrical switches which does not consume excessive spaceand is easily manufactured.

Further and additional objects of this invention will become manifestfrom a consideration of this description, the accompanying drawings andthe appended claims.

In one form of this invention a detent mechanism is ture 48 and a radialseverance whereby two resilient arcuate arms 59 and 52 are defined Thelength of the armprovided on a wafer type rotary electrical switch inwhich the detent mechanism includes a plate transverse to the switchshaft and having a circular pattern of undulations formed thereonconcentrically with the shaft. A spring web member is secured to theshaft spaced from the plate and the spring member has two arcuatecantilever arms with their free ends spaced apart and shaped toresiliently retain a ball therebetween and urge the ball against thecircular pattern of undulations.

For a more complete understanding of this invention reference will nowbe made to the accompanying drawing wherein:

FIG. 1 is a perspective view of a wafer type electrical switchincorporating one embodiment of this invention;

FIG. 2 is a sectional View of the switch of FIG. 1, taken on line 22thereof and illustrating the details of the detent mechanism;

FIG. 3 is a side view of a fragment of the switch mechanism of FIG. 1'showing the detent mechanism;

FIG. 4 is a top view of the detent mechanism with portions of theassociated switch omitted;

FIG. 5 is similar to FIG. 4 showing the shaft of the switch partiallyrotated;

FIG. 6 is a view similar to FIGS. 4 and 5 showing the switch mechanismrotated substantially to the mid-point between two positions; and

FIG. 7 is a view of the detent mechanism substantially the same as FIGS.4-6 showing the switch shaft fully rotated to the next contact position.

Referring now to the drawings and more particularly to FIG. 1, awafer-type electrical switch 10 is illustrated utilizing a detentmechanism 12 constructed in accordance with this invention. The switchmechanism consists of a central rotatable shaft 14 having a flattenedmajor portion 16. The shaft 14 is supported in an externally threadedbearing 18 and is secured thereto by a small snap ring 20 which seats ina recess 22 formed in shaft 14. Bearing 18 has a hexagonal portion 19 tofacilitate attachment to control panels and the like. A plate 24 whichforms a part of the switch mechanism also constitutes a portion of thedetent mechanism 12. The plate supports two elongate struts 26 and 28which, in turn, support switch wafers 30 and 32. The struts 26 and 28are secured in plate 24 and in wafer 30 by any appropriate means. In theinstant structure they are staked to plate 24 and retained in wafer'30by twisting the free end portion 34. While two wafers are here employed,it will be obvious that any number of wafers may be inserted merely bylengthening the shaft 14 and the struts 26 and 28. Central wafer 32haslugs 33 which are retained in appropriate apertures in the struts 26and 28.

Each wafer has a plurality of metallic contacts 36 secured thereto andthe contacts 36 are in engagement with a metallic annulus 38 supportedon an insulating disk 40. Disks 40 are rotatably suported in theirrespective wafers and have a generally rectangular central aperture toreceive the flattened portion 16 of shaft 14-. Thus rotation of shaft 14produces corresponding rotation of annular bridging contacts 38 whichcompletes circuits between preselected contacts 36.

To positively locate the bridging contacts 38 with respect to the fixedcontacts 36 the detent mechanism 12 is provided. Plate 24 has in thedescribed embodiment twelve protuberances or undulations 42 which areimiformly spaced in a circular pattern concentrically with the shaft 14.A spring web 44 is secured to the shaft 14 as by staked corners 46. Theweb 44 is spaced from the plate 24a predetermined small distance, asbest illustrated in FIG. 3. The web 44 is provided with an arcuateaperate severance 48 obviously determines the rigidity or resilience ofthe arms 50 and 52.

The free ends of arms 50 and 52 are formed outwardly at a substantialangle. Thus, as shown best in FIG. 4, the free end 54 of arm 50 extendsoutwardly away from plate 24 and forms an angle in the order of about 90with the free end 56 of resilient arm 52. A steel ball 58 is retainedbetween free ends 54 and 56 whereby the free ends 54 and 56 aredistorted slightly and urge the ball 58 against the plate 24. Under theinfluence of free ends 54 and 56 the wall will seat between two adjacentprotuberances or undulations 42a and 42b whereby the ball and, in turn,the web 50 and shaft 14 are positively oriented to a particular positionof rotation with respect to bushing 18 and wafers 42. The protuberances42a and 42b are shaped as shown in FIG. 4 to define a high centralportion with adjacent sloping sides about the circular pattern wherebycentering of the ball 58 between the adjacent protuberances isencouraged and insured.

As clearly shown in the figures the free ends 54 and 56 are shaped abouttheir longitudinal axes to form arcuate retainers for the ball 58 toprevent radial displacement of the ball and insure motion of the ball inthe predetermined circular pattern.

Operation of the detent mechanism is clearly illustrated in H63. 5, 6and 7. In FIG. the shaft 14 has been rotated slightly in the clockwisedirection indicated by arrows 60. In the particular embodiment hereindescribed there are twelve possible switch positions. Thus each positionrepresents an angular displacement of substantially 30. In FIG. 5angular movement of approximately has been imparted to shaft 14. In somoving shaft 14, it will be noted that web 50 which is secured to theshaft has also moved through the 10 angular displacement but in so doingthe ball 58 has remained somewhat behind and has been displacedto anangle slightly less than 10. This produces what may be termed a cockingaction of the detent mechanism. a

To permit relative displacement of web 50 and ball 58 free end 56 of arm52 has been distorted outwardly while free end 54 of arm 50 has relaxedsomewhat and has moved inwardly toward plate 24. This cocking action ofthe free ends 54 and 56 as the ball 58 is delayed by the resistance ofthe protuberance 42a is an important aspect of the operation of theinstant detent mechanism.

FIG. 6 illustrates an unstable transient condition of the detentmechanism where the shaft 14 has been rotated in the clockwise directionindicated by arrow 60 to a position somewhat in excess of 15 from thestarting point whereby the mechanism other than the ball 58 has alreadypassed the dead center between the two adjacent switch positions.However, because of the retarding effect of the protuberance 42a on ball58 the ball is substantially at the dead center position. As is clearfrom the drawing under this condition the free end 54 of resilient arm50 is substantially relaxed while the free end 56 of the resilient arm52 is distorted and under substantial tension. Thus the force ofresilient arm 52 against ball 58 will immediately cause the ball 58 tomove toward its normal position with respect to the two free ends 54 and56 and this will move the ball 58 beyond the dead center position onprotuberance 42a.

Merely releasing the rotational pressure on shaft 14 will thus permitthe ball to centerbetween protuberance 42a and'the next adjacentprotuberance 42c whereby the shaft 14 will positively locate in the nextswitch position, as illustrated in FIG. 7. This switch position isdisplaced 30 from the switch position illustrated in FIG. 4. It will beobvious that the switch functions in precisely the same 'manner at eachposition and that a multiposition switch having the unusual propertiesof quick action and positive contact closure is thereby provided by thisinvention.

While one particular embodiment of the detent mechanism has beendescribed in substantial detail, it will be immediately apparent toone'skilled in the art that the detent may be incorporated in othermechanisms and may be varied by alterating the size and shape of thevarious components such as the ball, the shape of the protuberances, andthe particular shape of the resilient arms and free ends thereof.

Without further elaboration, the foregoing will so fully explain thecharacter of my invention that others may, by applying currentknowledge, readily adapt the same for use under varying conditions ofservice, while retaining certain features which may properly be said toconstitute the essential items of novelty involved, which items areintended to be defined and secured to me by the following claims.

I claim:

1. A detent comprising bearing means, shaft means rotatably mounted onsaid bearing means, locating means fixed with respect to one of saidfirst two means, said locating means including a generally planarportion generally normal to the axis of said shaft means and protuberantportions radially spaced from said shaft means and extending outwardlyfrom the plane of said planar portion, two opposed resilient arm meanshaving free ends spaced apart circumferentially to define a space, saidresilient arms being fixed to the other of said first two means andradially disposed therefrom with the free ends thereof in predeterminedspaced relationship with respect to said planar portion and saidprotuberances, and a rotatable member retained in said space between thefree ends of said arm means and said protuberant portions, said armmeans being individually yieldable in response to rotation of said shaftmeans in said bearing means.

2. A detent comprising bearing means, shaft means rotatably mounted onsaid bearing means, locating means fixed with respect to said bearingmeans, said locating means including a generally planar portiongenerally normal to the axis of said shaft means and protuberantportions radially spaced from said shaft means and extending outwardlyfrom the plane of said planar portion in a generally circularconfiguration, two opposed resilient arm means having free ends spacedapart circumferentially to define a space, said resilient arms beingfixed to the other of said first two means rotatable with said shaftmeans and radially disposed therefrom with the free ends thereof inpredetermined spaced relationship in said space, and a rotatable ballmember retained between the free ends of said arm means and saidprotuberant portions, said arm means being individually yieldable inresponse to rotation of said shaft means in said bearing means.

3. A detent comprising bearing means, shaft means rotatably mounted onsaid bearing means, a plate secured to and extending radially outwardfrom said bearing means, said plate having means defining undulationsgenerally circularly disposed and concentric with said shaft means, aweb secured to said shaft means in spaced relationship with respect tosaid plate, two opposed resilient members extending from said web andhaving free resilient ends in circumferentially spaced relationship todefine a space between said free ends and said plate, and a rotatablemember retained in said space between said two free ends and said meansdefining undulations, said resilient members being individuallyyieldable in response to rotation of said shaft means in said bearingmeans.

4. A detent comprising bearing means, shaft means rotatably mounted onsaid bearing means, a plate secured to and extending radially outwardfrom said bearing means, said plate having means defining undulationsgenerally circularly disposed and concentric with said shaft means, aweb secured to said shaft means in spaced relationship with respect tosaid plate, two resilient members extending from said web and havingfree resilient ends in circumferentially spaced relationship to define aspace between said free ends and said plate, and a rotatable ball memberretained in said space between said two free ends and said meansdefining undulations, said members being individually yieldable inresponse to rotation of said shaft means in said bearing means.

5. A detent comprising bearing means, shaft means rotatably mounted onsaid bearing means, a plate secured to and extending radially outwardfrom one of said first two means, said plate having means definingundulations generally circularly disposed and concentric with said shaftmeans, a web secured to the other of said two means in spacedrelationship with respect to said plate, two resilient members extendingfrom said web and having free resilient ends in circumferentially spacedrelationship to define a space between said free ends and said plate,said free ends overlying said circularly disposed undulations and beingcircumferentially spaced, and a rotatable ball member retained in saidspace between said two free ends and said means defining undulations,said resilient members being individually yieldable in response torotation of said shaft means in said bearing means.

6. A detent comprising bearing means, shaft means rotatably mounted onsaid bearing means, a plate secured to and extending radially outwardfrom said bearing means, said plate having means defining undulationsgenerally circularly disposed and concentric with said shaft means, aweb secured to said shaft means in spaced relationship with respect tosaid plate, two resilient members extending from said Web and havingfree resilient ends in circumferentially spaced relationship to define aspace between said free ends and said plate, said free ends overlyingsaid circularly disposed undulations and being circumferentially spaced,and a rotatable ball member retained in said space between said two freeends and said means defining undulations, said free ends being arcuatelyformed to entrap said ball member against said undulations, saidresilient members being individually yieldable in response to rotationof said shaft means in said bearing means.

7. A detent for resiliently maintaining a shaft element in one of apredetermined plurality of positions of rotation relative to asupporting bearing element comprising locating means fixed with respectto one of said elements, said locating means including a generallyplanar portion generally normal to the axis of said shaft element andprotuberant portions radially spaced from said shaft element andextending outwardly from the plane of said generally planar portion, tworesilient arm means fixed to the other of said elements and radiallydisposed therefrom with the free ends thereof in predeterminedcircumferentially spaced relationship to define a space between saidfree ends and said locating means, and a rotatable member retained insaid space between the free ends of said arm means and said protuberantportions, said arm means being individually yieldable in response torotation of said shaft element in said bearing means.

8. A detent for resiliently maintaining a shaft in one of apredetermined plurality of positions of rotation rela tive to asupporting bearing means comprising locating means fixed with respect tosaid bearing means, said cating means including a generally planarportion generally normal to the axis of said shaft and protuberantportions radially spaced from said shaft and extending outwardly fromthe plane of said generally planar por tion, two resilient arm meansrotatable with said shaft and extending radially therefrom, the endportions thereof being arcuate and overlying said protuberant portions,the free ends of said end portions being circumferentially juxtaposedand angularly disposed with respect to said plane to define a spacebetween said free ends and said locating means, a rotatable ball memberbeing resiliently retained in said space between said end portions andurged against said protuberant portions, said arm means beingindividually yieldable in response to rotation of said shaft in saidbearing means.

9. A detent for resiliently maintaining a shaft in one of apredetermined plurality of positions of rotation rel ative to asupporting bearing means comprising locating means fixed with respect tosaid bearing means, said 10- cating means including a generally planarportion generally normal to the axis of said shaft and protuberantportions radially spaced from said shaft and extending outwardly fromthe plane of said generally planar portion, said protuberant portionsbeing generally uniformly spaced and circularly disposed concentricallywith said shaft, each of said protuberant portions having sloping sidewalls extending circumferentially from said plane, two resilient armmeans rotatable with said shaft and extending radially therefrom, theend portions thereof being arcuate and overlying said protuberantportions, the free ends of said end portions being circumferentiallyjuxtaposed and angularly disposed with respect to said plane to define aspace between said free ends and said locating means, a rotatable ballmember being resiliently retained in said space between said endportions and urged against said protuberant portions, said arm meansbeing individually yieldable in response to rotation of said shaft insaid bearing means.

10. A detent for resiliently maintaining a shaft in one of apredetermined plurality of positions of rotation relative to asupporting bearing means comprising locating means fixed with respect tosaid bearing means, said 10- cating means including a generally planarportion generally normal to the axis of said shaft and protuberantportions radially spaced from said shaft and extending outwardly fromthe plane of said generally planar portion, said protuberant portionsbeing generally uniformly spaced and circularly disposed concentricallywith said shaft, each of said protuberant portions having sloping sidewalls extending circu-mferentially from said plane, two resilient armmeans rotatable with said shaft and extending radially therefrom, theend portions thereof being arcuate and overlying said protuberantportions, the free ends of said end portions being circumferentiallyjuxtaposed and angularly disposed with respect to said plane to define aspace between said free ends and said locating means, each of said endportions having an arcuate cross section, a rotatable ball member beingresiliently retained in said space between said end portions and urgedagainst said protuberant portions, said arm means being individuallyyieldable in response to rotation of said shaft in said bearing means.

11. A detent for resiliently maintaining a shaft in one of apredetermined plurality of positions of rotation relative to asupporting bearing means comprising a plate fixed relative to saidbearing means and generally normal to the axis of said shaft, said platehaving a circular pattern of protuberances thereon radially spaced fromand concentric with said shaft, 2. generally circular resilient meanssecured to said shaft in spaced relationship to said plate, saidresilient means having an arcuate severance intermediate said shaft andthe periphery of said resilient means, and a radial severance betweensaid arcuate severance and said periphery whereby two resilient arms areformed, the free ends of said arms being angularly disposed outwardlyfrom said plate to define a space between said free ends and said plate,and a rotatable ball member being resiliently retained in said spacebetween said free ends and urged against said protuberances thereby,said arms being individually yieldable in response to rotation of saidshaft in said bearing means.

12. A detent for resiliently maintaining a shaft in one of apredetermined plurality of positions of rotation relative to asupporting bearing means comprising a plate fixed relative to saidbearing means and generally normal to the axis of said shaft, said platehaving a circular pattern of protuberances thereon radially spaced fromand concentric with said shaft, a generally circular resilient meanssecured to said shaft in spaced relationship to said plate, saidresilient means having an arcuate severance intermediate said shaft andthe periphery of said resilient means, and a radial severance betweensaid arcnate sev: erance and said periphery whereby two resilient armsare formed, the free ends of said arms being angnlarly disposedoutwardly from said plate and having an arcuate crnss section to definea space between said free ends and said plate, and a rotatable ballmember being resiliently retained insaid space between said free ends,said arms being individually yieldable in response to rotation 'of saidshaft in said bearing means and urged against said protuberancesthereby, radial displacement (if said ball member being prevented by thearcuate shape of said free ends.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS Great Britain July 16, 1931

